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Old 08-11-2012, 11:24 AM   #1
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Light only works when lead is wired to ground?


I have an outdoor light fixture that I am trying to replace. The house was built ten years ago.

When I removed the original lamp, I noticed one of the two leads was wired to the ground, and one was wired to the black wire, which is hot per my current sensor. There are three wires in the box - black, ground (bare copper), and white or neutral, all from a single romex cable. Unfortunately, I do not recall where the white was when I removed the original.

I wired the new lamp per the instructions, something I have done many times before - black to black, white to white, and bare copper ground to ground. Nothing. The lamp and bulbs are brand new, and I have tried four separate bulbs. I checked the black and neutral with my current sensor and with the switch on and the lamp installed this way, both show as hot. With the lamp not installed, the switch on, and the wires disconnected only the black shows as hot. The switch is single pole, and appears to be wired correctly with a black to each screw on one side and a copper ground on the other.

Assuming the new fixture was bad, I reinstalled the old fixture correctly - black to black, white to white, and bare copper ground to ground. Still nothing. No light, and I confirmed the bulb is good by putting it in another lamp. The only way to get it to light is to connect the neutral in the lamp to the bare copper ground.

I capped the wires, turned the circuit back on, and identified all the outlets, switches and fixtures on the same circuit. I opened every one of them up (four lights and eight outlets) and found three (one switch and two fixtures in another room) where multiple commons connect. All were properly connected. My outlet tester shows all outlets as "correct". I found no instances of grounds connected to commons or vice-versa.

Any ideas? Is it proper to wire this thing the way I found it?

Thanks for any and all advice!


Last edited by dhartlein; 08-11-2012 at 11:44 AM.
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Old 08-11-2012, 12:10 PM   #2
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Light only works when lead is wired to ground?


When you say bare on the other side of the switch, do you mean a 3 way switch?
Does the switch say off and on?

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Old 08-11-2012, 12:22 PM   #3
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Light only works when lead is wired to ground?


Sounds like the wiring has an open neutral so they used the grounding conductor to compensate. get r done! lol....

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Old 08-11-2012, 12:34 PM   #4
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Light only works when lead is wired to ground?


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Sounds like the wiring has an open neutral so they used the grounding conductor to compensate. get r done! lol....
Either that or a bare wire on a 3 way!
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Old 08-11-2012, 01:22 PM   #5
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Light only works when lead is wired to ground?


OK - thought it was a two way, but it says off and on on the switch. Is it?

Facing the switch, there are two black wires on the right side, and a copper ground wire is attached to a green colored screw on the bottom left - looks like it goes into the frame of the switch as opposed to being a contact. There are no other screws on the left side of the switch.

There are two white wires in the switch box, twisted together and capped.

So..... what do I need to do here? Thanks gentlemen!
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Old 08-11-2012, 01:28 PM   #6
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Light only works when lead is wired to ground?


Your tester indicated the white wire was "hot" because it is broken somewhere in the wall, and receiving back-fed juice through the light bulb.

The white wire should never indicate "hot" in such a scenario.

You need to replace the cable from the switch to the light fixture IF the white wire tests out "good" at the switch. Otherwise, it is broken before the wall switch (maybe at the outlet that feeds it)?
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Old 08-11-2012, 01:38 PM   #7
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Light only works when lead is wired to ground?


sounds like a single pole switch to me

i would say open Neutral. the only reason the light works when making contact with the ground is because this completes the light circuit.
to complete a circuit the Neutral wire should be used. using a bare ground for return current is dangerous.

find the open neutral using a Digital Volt Ohm Meter.
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Old 08-11-2012, 01:56 PM   #8
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Light only works when lead is wired to ground?


We have just jumped past my skill level..... am going to need to hire a professional the way it sounds.

This wiring is in an exterior wall of a brick two story house. The light is in the ceiling of an exterior porch - up four feet from the switch, over four and then out three or so. I was a little surprised with the circuit - some of the outlets are in the room with the switch, some in the foyer, some in the garage. The lights are in the the garage and room with the switch, which are adjacent to each other. Weird thing is not all the outlets in the garage and in this room are on the same circuit. So figuring out where the feed comes from is well over my head.

How will an electrician find the problem here?

Thanks again. Guess I am glad I tried to install the light and found the issue. My wife's line is we bought a 10 year old house that thinks it's 40. Here we go again!

Last edited by dhartlein; 08-12-2012 at 03:37 PM.
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Old 08-12-2012, 03:39 PM   #9
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Light only works when lead is wired to ground?


FWIW - found some blackening on one of the two common lines in the switch box to the porch. That can't be good.
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Old 08-12-2012, 10:23 PM   #10
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Light only works when lead is wired to ground?


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Originally Posted by dhartlein View Post
We have just jumped past my skill level.

How will an electrician find the problem here?

Starting at the fixture working backwards he will open up boxes to find out where the neutral was lost. I doubt it will take much to find it.
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Old 08-13-2012, 05:44 AM   #11
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Light only works when lead is wired to ground?


Thanks!
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Old 08-17-2012, 01:47 PM   #12
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Light only works when lead is wired to ground?


UPDATE -

Hired an electrician to come out - charged me $99 and diagnosed the problem as a broken neutral line to the light from the switch. Only checked that one line, and poked around the breaker box to make sure everything was tight, but his conclusion made sense to me. To access the line, I decided on the DIY route as I would have to pull crown molding, fascia board and a plywood ceiling from the porch. No big deal.

BUT - later that evening, and before doing anything, I decided to hook the original light up with some old romex I had inside at the switch to determine what line went to the light, and which fed the switch. Just curious. Both neutrals were bad. Hmmmm..... called the owner of the electrical company the next morning and asked him to come back out. He got pretty irritated, claiming he should have charged me more the day before (he originally quoted me $19 for a repair estimate, it went to $99 with the guy on site), and later calmed down and said he would come over personally that afternoon. I took off work, and he was a no show after waiting for three hours. One of his guys called well past three hours late and said he would arrive in a couple of minutes - again, the owner insisted he would come himself earlier that morning - but was in the wrong city 30 miles away. I told him to tell his boss I would work on it myself.

So, I started back tracking from the hot from the box where the circuit originates, determining which line fed the porch switch through process of elimination. After moving four outlet and switch boxes along the circuit I finally found it - the one disconnect that killed the switch hot but left everything else on the circuit active - and something else. One of the outlets had a missing tab on the neutral side, with the hot tab still in place. Replaced the outlet, and voila, everything lit up as it should including the two lines that supposedly had to be replaced. The original porch lamp functioned, for the first time, when wired correctly. No more open neutral.

I replaced all switches and outlets on the circuit out of paranoia, and went to Lowe's this morning and bought a multi tester. After confirming I had 120 on the nose outside between hot and ground and hot and neutral, and the same on all the other switches and outlets, and my little outlet tester show they were all correct, I felt pretty good all the lines are fine, and the original "diagnosis" was a step toward one heck of an estimate and repair bill. I liked the electrician that I paid $99 and trusted him - but he quoted 7-900 to pull new wire. Had it been half that, my ceiling would probably be down right now for no reason. Had I not checked the other side of the switch and found open neutral there too, same answer, but I would be knee deep in the demolition right now for no reason.

Instead, the new light is in and all is well. Thanks to you guys for giving me the info to think this through. Life, and this forum, is good!

Last edited by dhartlein; 08-17-2012 at 01:58 PM.
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Old 08-17-2012, 02:02 PM   #13
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Light only works when lead is wired to ground?


Any company that says they'll do a repair for 19 bucks is suspect in my mind. I won't even get in my car for that. Classic case of you get what you pay for. Any sparky worth his salt would have done a lot more than just say bad neutral, you need a new wire pulled.

On a lighter note problem solved the problem and you earned some valuable experience. Congrats!!
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Old 08-17-2012, 05:46 PM   #14
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Light only works when lead is wired to ground?


Well done! That's some good troubleshooting. I wonder why the original electrical contractor didn't figure that out during construction?
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Old 08-17-2012, 11:01 PM   #15
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Light only works when lead is wired to ground?


Kudos. Now you,ve just enough knowlege to make you dangerous j/k, good work.

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